Chapter 5 Tissues
Tissues-a group of similar cells that performs a specialized function
4 types of tissues
1. Epithelial
2. Connective
3. Muscle
4. Nervous
5.2 Epithelial Tissue
- covering organs, forming inner linings of body cavities, and lining hollow organs
basement membrane-layer of non-living material that anchors epithelial tissue to underlying connective tissue
-lack blood vessels get nutrients from underlying connective tissue
-readily divide, heal rapidly
-tightly packed
Classified according to shape and number of layers of cells
- Simple- single layer of cells
- Stratified-two or more layers of cells
- Squamous-thin flattened cells
- Cuboidal-cube-shaped cells
- Columnar-elongated cells
1. Simple squamous epithelium- single layer of thin, flattened cells that are fit tightly together
-substance pass easily through
-line the air sacs of lungs
-forms walls of capillaries
-lines insides of blood and lymph vessels
-covers membranes that line body cavities
2. Simple cuboidal epithelium-single layer of cube-shaped cells
-cover the ovaries
-lines most of the kidney tubules
-lines the ducts of glands, such as salivary, thyroid, pancreas, and liver.
3.Simple Columnar Epithelium-single layer of elongated cells
-tissue is thick
-lines the uterus and most organs of the digestive tract
4 Pseudostratified Columnar
Epithelium-appear layered but are not
-commonly have cilia
-line the passages of the respiratory system
5. Stratified Squamous Epithelium- many cell layers make it relatively thick
-forms outer layer skin
-line the mouth, throat, vagina, and anal canal
- Stratified Cuboidal Epithelium-consists of two or three layers of cuboidal cells that form the lining of a lumen
-line the ducts of the mammary glands, sweat glands, salivary glands, and pancreas.
-also forms the lining of developing ovarian follicles and seminiferous tubules
7. Stratified Columnar Epithelium-several layers of cells
-found in the male urethra and vas deferens and the pharynx
8. Transitional Epithelium-specialized to change in response to increased tension
-forms the inner lining of the urinary bladder and lines the uterus and part of urethra
9. Glandular Epithelium-composed of cells that are specialized to produce and secrete substances into ducts or into body fluids
Exocrine glands-secretes its products into a duct or onto a body surface
3 types
- Merocrine glands-secretes a fluid without losing cytoplasm
2.Apocrine glands-secretions contain parts of secretory cells
3. Holocrine glands-secretion contains entire secretory cells
Endocrine glands-secretes hormones directly into the blood or body fluids
5.3 Connective Tissues
-bind structures, provide support, serve as framework, fill spaces, store fat, produce blood cells, protect against infections, and repair tissue damage
matrix-intercellular material of connective tissue
Major Cell types
- Fibroblasts-
- produce fibers by secreting proteins into the matrix
- most common type of cells
2. Macrophages-
-specialized to carry on phagocytosis
-function as scavenger and defensive cells that clear foreign particles from tissues
- Mast cells-located near blood vessels
-release heparin, which prevents blood clotting
-release histamine, which promotes reactions associated with inflammation and allergies
Fibroblasts produce three types of connective tissue fibers
- Collagenous fibers-
-flexible, slightly elastic, resist pulling force
-hold structures together, such as ligaments and tendons
2. Elastic fibers-
-common in body parts that are frequently stretched such as vocal cords
3. Reticular Fibers-
-highly branched and form delicate supporting networks in a variety of tissues
Categories of Connective Tissue
1.Connective Tissue Proper
- Loose-areolar
-binds the skin to the underlying organs and fills spaces between muscles
- Adipose tissue or fat- lies beneath the skin, in spaces between muscles, abdominal membranes, on the surface of the heart, and around certain joints
-cushions joints and some organs
-insulates beneath the skin
-stores energy in fat molecules
- Dense- has few cells, very strong enabling the tissue to withstand pulling forces
-binds body parts together
-in the protective white layer of the eyeball
-in deeper skin layers
Specialized Connective Tissues
- Cartilage-rigid connective tissue, provides support, framework, and attachments.
-protects underlying tissue and forms structural models for developing bones
chondrocytes-cartilage cells
3 types of cartilage
A. Hyaline-most common
-found on the end of bones in many joints
-soft part of nose
-supporting rings of the respiratory passages
B. Elastic-more flexible than hyaline
-provides framework for the external ears and for parts of the larynx
C. Fibrocartilage-shock absorber
-forms pads between individual bones of the spinal column
-cushions bones in the knee and in the pelvic girdle
2. Bone-most rigid connective tissue
-hardness is due to mineral salts between cells
-internally support body structures
-protects vital parts in the cranial and thoracic cavities
-attachment for muscles
-contains red marrow, forms blood cells
osteocytes-bone cells
3.Blood-
-transports materials between interior body cells and those that exchange substances with the external environment
-composed of formed elements suspended in a fluid matrix called blood plasma
Muscle Tissues:
-are contractile, can shorten
-as they contract, they pull at their attached ends, and this moves body parts
Three types
- Skeletal Muscle Tissue-
-Found in muscles attached to bones
-Voluntary muscles-controlled by conscious effort
-Have striations, alternating light and dark cross-markings
-Move the head, trunk, and limbs
-Make facial expressions, write, talk, sing, chew, swallow, and breathe
- Smooth Muscle Tissue-
-Does not have striations
-Tissue comprises the walls of hollow internal organs, such as stomach, intestine, urinary bladder, uterus, and blood vessels
-They are involuntary
- Cardiac Muscle Tissue-
-Only in the heart
-Makes up most of heart and pumps blood through heart chambers and into blood vessels
-Controlled involuntary
Nervous Tissues-
-Found in the brain, spinal cord, and peripheral nerves
-Basic cell is called neurons (nerve cells)
-Transmit nerve impulses along cytoplasmic extention
-Coordinate, regulate, and integrate many body functions